Technical Field
This application is generally related to thin film manufacturing, and more particularly, to the cleaning of reactors used in depositing thin films.
Description of the Related Art
In the manufacture of integrated devices, thin films are deposited or formed on substrates in a reaction chamber or reactor, for example, by chemical vapor deposition (CVD) or atomic layer deposition (ALD). In these deposition processes, the film materials are also deposited on other surfaces, for example, on the walls and other exposed surfaces of the reaction chamber, thereby contaminating these surfaces. Over time, these materials accumulate and build up, eventually flaking, shedding, and/or delaminating particles from the surface of the reaction chamber. Particles that land on a surface of a substrate, for example, either falling on the surface or carried in a gas stream, can cause problems in the manufacturing process, for example, by reducing the yield and/or reproducibility of the process. Periodically cleaning the contaminants from the reaction chamber can reduce these problems.
One method for cleaning a reaction chamber is by in situ etching cycles using one or more cleaning cycles of suitable etchants. In situ cleaning reduces the need to remove, replace, and/or requalify a contaminated reaction chamber. In cases in which the etch rates are high, in situ etching can be performed as often as necessary without significantly affecting the tool's throughput. Lower etch rates can reduce throughput, however. Moreover, in some cases in situ etching exhibits one or more drawbacks, for example, significantly etching one or more components of the reaction chamber, causing substrate contamination, and/or causing environmental, health, and safety (EHS) problems. Consequently, in some cases, in situ cleaning is not feasible.
Another option for cleaning reaction chambers is ex situ cleaning, in which the contaminated components are removed from service for cleaning. “Bead blasting” is a form of ex situ cleaning by mechanical abrasion in which a stream of an abrasive grit, for example, alumina, zirconia, glass, silica, SiC, or other suitable material, is impinged against a surface-to-be-cleaned, for example, using a high-pressure fluid stream. Bead blasting has several shortcomings, for example, damage can be caused to the reaction chamber components by the cleaning process, thereby reducing their lifetimes. Bead blasting is a “line of sight” process, resulting in difficulty in cleaning high aspect ratio components. Due to an inability to visually monitor the removal of the contaminant(s), an endpoint not apparent, such that, when the contaminant is removed and the underlying material is reached; there is a chance of missing a contaminated area. Bead blasting can also cause contamination of the cleaned part by the abrasive material. Contaminants that are as hard or harder than the abrasive material cannot easily be removed by bead blasting. Bead blasting also entails high cost and low reproducibility.